Reducing irrigation system water pressure

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MikeAqua

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#207973 21-Jan-2017 16:18

Will two sequential pressure reducers (Like This) reduce pressure more than single one?

I've just split my irrigation from 2 zones into 4 zones, controlled by a tap mounted 4-zone controller

Both zones had one 19mm main line and one 13mm branch each.

Now the 13mm lines are separate zones.

Nothing has changed within them, but all off sudden they are leaking where 4mm lines tap into the 13mm line. So I bought a pressure reducer. This reduced the leaks but didn't eliminate them.

I'm now wondering if I put two pressure reducers on each line, will this help?

Mike

richms

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#1707028 21-Jan-2017 16:26

They seem to, In moving a pipe around for builders and hooking it into a different part of my system I ended up with 2 of them inline with some of the baskets, and the flow was reduced to almost nothing and the plants died before I noticed it.

Richard rich.ms

BruceHamilton

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#1707036 21-Jan-2017 16:44

Yes, it will help, depending on the downstream pressure of the first one. According to the Neta catalogue, their pressure reducer will reduce kPa Inlet/Outlet 100/75, 200/100, 300/115, 400/125, 500/145.

neb

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#1707087 21-Jan-2017 19:06

Why not put in a stop/globe valve? That way you can control the pressure to the exact level you need, rather than having to cascade pressure-reducers and hope you get the right level. Note that what you want is a globe valve that allows linear adjustment of flow, not a full-flow valve like a gate or ball valve which is meant to be operated only in the fully open or closed position, if you run it partially open you get erosion of the metal portions leading to eventual failure.

andrewNZ

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#1707257 21-Jan-2017 22:43

neb: Why not put in a stop/globe valve? That way you can control the pressure to the exact level you need, rather than having to cascade pressure-reducers and hope you get the right level. Note that what you want is a globe valve that allows linear adjustment of flow, not a full-flow valve like a gate or ball valve which is meant to be operated only in the fully open or closed position, if you run it partially open you get erosion of the metal portions leading to eventual failure.

A valve like that controls flow not pressure. It'll work in the short term, but it isn't much of a solution really. Any changes in the system, like mods, kinks or blockages can significantly alter the pressure.

Jase2985

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#1707280 22-Jan-2017 08:01

what is pressure caused by? a restriction to flow

if there is not enough flow then the pressure cant build up enough because the outlet still has some flow from it.

its no different to just turning the tap down a little on your hose which has a nozzle attached and you dont want it to spray as far. all your have done is reduce the flow at the tap which has the outcome of reducing the pressure in hose

MikeAqua

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#1707560 22-Jan-2017 17:45

Thank for the suggestions.

I've also remembered that I have the adjustable sprinkler heads and drippers on this line turned down to very flow because it used to be on for long time. As I can reduce the cycle length now I can increase their flow rate, which should decrease pressure in the line.

If that doesn't work I think I'll try doubling up the pressure reducers. It's very easy to try as an experiment.

Ball valves tend to be finicky things to adjust, so I'd rather not go there.

Mike

MikeAqua

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#1708804 24-Jan-2017 15:49

Fixed by replacing barb-thread 4mm connectors with barb-barb 4mm connectors.

It turns out the threads are designed for the vertical riser tubes not the 4mm hose, which is softer and increasing the pressure exposed this mistake.

Mike

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richms

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#1708809 24-Jan-2017 15:55

I find that where the 4mm hose gets hot in the sun it will get so soft that the pressure will just push it off the barbs without a cable tie over the hose below the barb. Doesnt seem to affect the barbs hold into the 12mm pipe tho.

Richard rich.ms

MikeAqua

7785 posts

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#1709226 25-Jan-2017 10:21

richms:

I find that where the 4mm hose gets hot in the sun it will get so soft that the pressure will just push it off the barbs without a cable tie over the hose below the barb. Doesnt seem to affect the barbs hold into the 12mm pipe tho.

Thanks for the heads up.

Theoretically they shouldn't get any sunlight where I have them installed but I'll keep an eye on it and I have some small cable ties on-standby.

Mike

1eStar

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#1709410 25-Jan-2017 14:14

Pays to put hose clamps on regardless. My folks' system blew a hose under the house, which undoubtedly caused a bit of consternation amongst the resident feral community, not to mention a bit of water damage.

MikeAqua

7785 posts

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#1709417 25-Jan-2017 14:25

1eStar: Pays to put hose clamps on regardless. My folks' system blew a hose under the house, which undoubtedly caused a bit of consternation amongst the resident feral community, not to mention a bit of water damage.

I haven't seen a clamp for the 4mm hose, which is why i think cable tie were suggested.

But I do use hose clamps at all the 13mm and 19mm connections - tails, tee's, elbows etc etc. I use stainless steel jubilee clamps not those hopeless plastic clamps sold in the irrigation section at hardware stores.

Mike

richms

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#1709442 25-Jan-2017 15:04

Just make sure you get the proper stainles clamps, I got one lot that turned out to be part stainless and the screw in it totally rusted up and I couldnt undo it. Not sure how long it would hold for but I found it when I needed to relocate a pipe and ended up having to cut the T off and replace it rather than re-use it.

Richard rich.ms

MikeAqua

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#1709471 25-Jan-2017 16:00

richms:

Just make sure you get the proper stainles clamps, I got one lot that turned out to be part stainless and the screw in it totally rusted up and I couldnt undo it. Not sure how long it would hold for but I found it when I needed to relocate a pipe and ended up having to cut the T off and replace it rather than re-use it.

The type I'm using are stainless band and driver. I use the same type in the bilge of my boat too they don't rust there.

Mike

D1023319

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#1709506 25-Jan-2017 17:10

My father uses a toilet cistern raised to 7 foot to provide reduced pressure for his greenhouse irrigation system.